Today on TV

So You Think You Can Dance (7 p.m., Ch. 13): The four remaining contestants perform; a winner will be declared Thursday. (And, with Chelsie Hightower's exit last week, there's nobody left with Utah ties.)

Baby Borrowers: Lessons Learned (8 p.m., Ch. 5): NBC is calling this a town hall meeting  a follow-up discussion that will feature both the teens who borrowed babies to learn what it was like raising them and the parents who loaned the infants.

Nova scienceNOW (8 p.m., Ch. 7): Reports on a pill to extend the human life-span; space elevators; and using satellites in archaeology.